Diastereoselective sp2–sp3 coupling of sugar enol ethers with unactivated cycloalkenes: new entries to C-branched sugars

Abstract

Sugar enol ethers undergo efficient coupling at C-2 with unactivated cycloalkenes under a low Pd loading affording allylic substitution products. High diastereoselectivity was observed at the allylic centre with sterically hindered substrates. Generation of a π-allyl complex by the Pd(II) catalyst via cleavage of the allylic C–H bond of the cycloalkene may be responsible for the formation of sp²–sp³ coupling products.